25x25x 1/2 Half Inch Ring Panel MERV 7 Furnace Air Filters 6 PackNordic Pure Half Inch Ring Panel AC Furnace Air Filters consist of an internal frame bonded between flat layers of two different types of electrostatically charged HVAC furnace filter media. The first layer is a high capacity, polyester filter material which acts as a pre filter, capturing large airborne particles. The second, more efficient, layer is a MERV rated smooth poly blend filter material. The electrostatic charge works as a magnet to draw in